1. Field
This disclosure relates to a luminescence biotin-transition metal complex conjugate and a method of amplifying signals using the same.
2. Description of the Related Art
The extremely strong binding interaction between biotin and (strept)avidin has widespread bioanalytical applications such as the detection of biomolecules, clinical diagnosis, and immunoassays. Of the many techniques for biotin-(strept)avidin assays, there has been considerable interest in transition metal complexes using phosphorescence to overcome the problems of organic fluorophores such as the strong pH dependence, low photostability, small Stokes shifts, and short lifetimes. Among the transition metal complexes using phosphorescence, Ir(III) complexes are promising candidates in various bioanalytical applications on account of their intense emission, wide range of emission energies, and high luminescence quantum yield. However, most ionic transition metal complexes developed as biological labeling reagents did not show high sensitivity upon binding to (strept)avidin. For example, the luminescence enhancement factor of previous transition metal complexes upon binding to (strept)avidin is usually in the range of about 1-3 fold. This is because the luminescence enhancement only results from the increased hydrophobicity of the surrounding environment of the bound probes, compared with the environment of the free probes.